Soldiers wearing protective clothing prepare to lift a tow truck in Hyde Road, Gillingham, Dorset, England as the investigation into the suspected nerve agent attack on Russian double agent Sergei Skripal continues Wednesday March 14, 2018. The army cordoned off a road in Dorset on Wednesday as the investigated the attack on Sergei Skripal and his daughter Yulia. Authorities have cordoned off several sites in and near Salisbury, 90 miles (145 kilometers) southwest of London as part of their probe. (Andrew Matthews/PA via AP)

The Canadian government has backed British claims that Vladimir Putin’s government “almost certainly” approved a poison attack against a former Russian spy and his daughter in the U.K. earlier this year.

The expression of support was delivered in a joint statement with the U.S., Germany and France on Thursday as Western allies sought to present a united front against — and ratchet up public pressure on — the Kremlin.

The statement came after British authorities accused two Russian nationals of attempting to kill Sergei Skripal and his daughter, Yulia, with the nerve agent Novichok in the city of Salisbury in March.

British Prime Minister Theresa May described the suspects as Russian military intelligence officers and alleged the March attack in Salisbury was approved by senior government officials in Moscow.

British Security Minister Ben Wallace went further, saying Putin himself was ultimately responsible for the attack.

Russia has repeatedly denied any involvement in the attack, which also sickened a British police officer and been linked to the death of a British woman, Dawn Sturgess, who accidentally came in June came contact with the same substance, which was developed by the Soviet Union as a chemical weapon.

Canada and its allies, however, said they had “full confidence in the British assessment that the two suspects were officers from the Russian military intelligence service … and that this operation was almost certainly approved at a senior government level.”

They demanded Russia open its Novichok program to international inspectors, urged anyone with information about the attack to speak to authorities — and vowed to disrupt “the hostile activities of foreign intelligence networks on our territories.”

The Salisbury attack has both resurrected memories of the Cold War and become a symbol of a new era of tensions between Moscow and the West that started in earnest in 2014 with Russia’s annexation of Crimea from Ukraine.

Relations between Canada and Russia have not been spared, with the two countries involved in various wars of words and tit-for-tat diplomatic expulsions — including one round in March that was in direct response to the Salisbury attack.

Prime Minister Justin Trudeau has described the attack as “unacceptable and unlawful,” and insisted Canada would work with the U.K. and its allies to hold Russia to account.

Moscow has maintained it was not involved, with Russian Ambassador to the UN Vassily Nebenzia saying on Thursday the latest allegations by London and its allies were designed “to unleash a disgusting anti-Russian hysteria.”

Putin’s spokesman, Dmitry Peskov, described the allegations levelled against Russian president and his government as “unacceptable.”

British authorities announced on Wednesday said two Russians, Alexander Petrov and Ruslan Boshirov, were being charged in absentia for the Salisbury attack after a lengthy investigation.

Russian officials have said they don’t recognize the suspects — whose names are believed to be aliases — and Peskov said Russia “has no reasons” to investigate them because Britain had not asked for legal assistance in the case.